//Given an array nums with n objects colored red, white, or blue, sort them in-p
//lace so that objects of the same color are adjacent, with the colors in the orde
//r red, white, and blue. 
//
// We will use the integers 0, 1, and 2 to represent the color red, white, and b
//lue, respectively. 
//
// You must solve this problem without using the library's sort function. 
//
// 
// Example 1: 
// Input: nums = [2,0,2,1,1,0]
//Output: [0,0,1,1,2,2]
// Example 2: 
// Input: nums = [2,0,1]
//Output: [0,1,2]
// Example 3: 
// Input: nums = [0]
//Output: [0]
// Example 4: 
// Input: nums = [1]
//Output: [1]
// 
// 
// Constraints: 
//
// 
// n == nums.length 
// 1 <= n <= 300 
// nums[i] is 0, 1, or 2. 
// 
//
// 
// Follow up: Could you come up with a one-pass algorithm using only constant ex
//tra space? 
// Related Topics 排序 数组 双指针 
// 👍 900 👎 0


package leetcode.editor.cn;

//Java：Sort Colors
class P75SortColors {
    public static void main(String[] args) {
        Solution solution = new P75SortColors().new Solution();
        // TO TEST
        solution.sortColors(new int[]{2, 0, 1});
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class Solution {
        public void sortColors(int[] arr) {
            //low记录low
            int low = 0, mid = 0, high = arr.length - 1;
            while (mid <= high) {
                switch (arr[mid]) {
                    case 0:
                        swap(arr, low, mid);
                        low++;
                        mid++;
                        break;
                    case 1:
                        mid++;
                        break;
                    case 2:
                        swap(arr, mid, high);
                        high--;
                        break;
                }
            }
        }

        public void swap(int[] arr, int i, int j) {
            int temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}